Steering transmission mechanism and vehicles with rigidly mounted axles incorporating said mechanism

ABSTRACT

Vehicles of various types having rigidly mounted axles include a steering transmission mechanism comprising a plurality of shafts, gears and clutches capable of both driving and steering the vehicles. The plurality of clutches which may be selectively energized serve to interconnect selected gears with their supporting shafts to provide the left and right sets of wheels, tracks or rollers separately with power in either the forward or reverse directions at more than one speed.

United States Patent 1191 [111 1 3, Kaltenegger 1 1 Oct. 9, 1973 [5STEERING TRANSMISSION MECHANISM 2,124,708 7/193 Peter l80/9.62 ANDVEHICLES WITH RIGIDLY MOUNTED r1 2 2 e ourneau AXLES INCORPORATING SAID2,866,360 12/1958 Gerst et a1. 180/62 x MECHANISM 2,999,553 9/1961Schwartz l80/6.7 [76] Inventor: Benn Ka|tenegger,KurhauSSt|- 3,195,4297/1965 Cowley 180/20 X 77-79 5202, Hennef, Sieg,

Germany Primary Examiner-Benjamin Hersh Assistant Examiner-Leslie J.Paperner [22] 1972 Attorney-Neil F. Markva et al. [21] Appl. No.:228,678

[57] ABSTRACT [30] Foreign Application Priority Data Feb 26 1971 GermanyP 21 09 177 0 Vehicles of various types having r1g1dly mounted axlesinclude a steering transmission mechanism comprising Feb. 26, l97lGermany P 21 09 120.3 a plurality of Shafts, gears and clutches capableof [52] U 8 Cl 180/6 2 180/9 62 180/20 both driving and steering thevehicles. The plurality of [51] 3 1 11/12 clutches which may beselectively energized serve to [58] i 2 6 66 6 7 interconnect selectedgears with their supporting 15 3 shafts to provide the left and rightsets of wheels, tracks or rollers separately with power in either the[56] Reerences Cited forward or reverse directions at more than onespeed.

UNITED STATES PATENTS 6 Claims, 11 Drawing Figures 3,0l7,94l 1/1962Baker ISO/6.2

I r l\ PMENTEU BET 9 5 SHEET 2 OF 6 FIG. 3

SHEET B [1? 6 FIG.10

STEERING TRANSMISSION MECHANISM AND VEHICLES WITH RIGIDLY MOUNTED AXLESINCORPORATING SAID MECHANISM SUMMARY OF THE INVENTION This invention isdirected to a steering transmission mechanism and to vehicles such ascrawler tractors, rollers or the like having rigidly mounted axles whichinclude the steering transmission mechanism.

Vehicles having drive wheels for crawler tracks or functional purposessuch as compacting rollers usually are arranged so that their axles arerigidly mounted on the frame of the vehicle. With this arrangement, itis not possible to swivel or pivot the wehels with respect to thevehicle for the purposeof steering in the conventional manner. Inaddition, the rigidly mounted drive wheels or rollers are usuallydisposed in pairs on each side of the frame. Each pair of wheels is thusarranged in tandem, one behind the other, in the direction of travel.The pairs of wheels on opposite sides of the vehicle are adapted to bedriven either jointly or independently. Commonly, with this arrangement,separate reversing gear mechanisms and drive transmissions are providedwith each pair of wheels or rollers so that each pair may be drivenindependently of the other. With this arrangement each pair can bedriven at a selected forward speed or reverse speed or can be disengagedto freely rotate. With each pair of wheels or rollers being controlledseparately, the vehicle can be caused to follow a curved path or evenrotated on the spot.

The conventional drive mechanism for a vehicle of this type thereforerequires a considerable amount of space in the vehicle. In addition, itis not possible to cause the vehicle to travel along a curved path whilemaintaining optimum control, since with this arrangement, normally onlyone pair of wheels or rollers will be driven while the other pair is notdriven or may even be braked. Thus, one track, pair of wheels or pair ofrollers located on the inside of the curve is pennitted or required toslip or slide. When sudden changes in direction take place, thischaracteristic will in many cases tear up or gouge the road surfacewhich is undesirable, particularly in the case of a roller vehicledesigned to smooth or compact a surface.

OBJECTS OF THE INVENTION It is an object of this invention to provide asteering transmission for vehicles having rigidly mounted axles whereina single transmission unit which is extremely compact is arranged toperform all of the necessary functions for both driving and steering thevehicle in both forward and reverse directions.

It is another object of this invention to provide a transmission for avehicle having rigidly mounted axles which includes only spur gearswhich remain pennanently meshed and do not require engaging ordisengaging or sliding in order to change speed or direction of thevehicle.

A still further object of this invention is to provide a vehicle havingrigidly mounted axles with a transmission which permits the wheels,rollers or tracks of the vehicle to be continuously driven while thevehicle is in motion so that none of the drive wheels, rollers or tracksare allowed to slide or slip on the supporting surface while the vehicleis following a curved path.

Another object of the invention is to provide a transmission for avehicle having rigidly mounted axles which does not include adifferential, thus permitting the vehicle to travel along a curved pathwhile constraining the wheels, tracks or rollers in a controlled manner.

A still further object of this invention is to provide a steeringtransmission mechanism having separate output shafts which areindependently controlled for speed and direction of rotation so that thedrive shafts on each side ofa vehicle may be controlled selectively andindependently in order that the vehicle may be made highly maneuverable.

A still further object of the invention is to provide a steeringtransmission mechanism requiring a simple and reliable control mechanismfor controlling operation of a vehicle.

SUMMARY OF THE INVENTION An extremely compact power transmission unitmounted on a vehicle is coupled to the drive shaft of an engine. Thetransmission has a plurality of arranged gears and shafts which providesa split transmission train for dividing the input power and deliveringit to separate output drive shafts, each output drive shaft beingcoupled to the wheels, track or rollers on one side of the vehicle. Onlyspur gears are used throughout the transmission which are permanentlymeshed, eliminating the necessity for engaging and disengaging thegears. Instead, clutches, preferably of the hydraulic type which areconveniently controlled by the application and release of hydraulicpressure, are mounted within the transmission and arranged tointerconnect selected gears with their rotational support shafts. It isthus possible through engagement of the appropriate coupling or clutchto drive either output shaft at a selected speed in either a forward orreverse direction. A pair of clutches wherein one performs a forwardfunction and the other a reverse function can be mounted on the sameshaft so that the meshed gear train for the desired function can beconnected to the particular drive shaft when desired. In the case ofhydraulically operated clutches, a hydraulic pump is directly connectedto the input drive shaft of the transmission providing a continuoussource of hydraulic pressure. A hydraulic valve is located in eachconduit line to each hydraulic clutch to control the engagement anddisengagement of each clutch. Conveniently, a two-way valve shaft can beused for controlling a pair of clutches mounted on a single shaft sinceonly a single function for the shaft will be required at any one time.In this way, only half the usual number of control valves is required.

By proper manipulation of the control valves, the pairs of wheels,tracks or rollers on each side of the vehicle can be operated jointly orindependently as desired. Thus, the vehicle can move in a forward orreverse direction at a predetermined speed. By independently controllingeach track or each pair of wheels or rollers, the vehicle can be turnedon the spot or driven alonga curved path either in the forward orreverse direction. All the travel movements of a vehicle of this designare constrainedly controlled so that the steering of the vehicle,particularly when traveling on curves, can be effected in anunequivocally defined manner. A road roller vehicle of this design isespecially suitable for use on sporting grounds having a plurality ofarcuate tracks. It is thus possible to roll a curved track evenlywithout it being necessary to effect sudden and sometimes erraticcontrols.

BRIEF DESCRIPTION OF DRAWINGS Other features of this invention willappear in the following description and appended claims, reference beingmade to the accompanying drawings forming a part of the specificationwherein like reference characters designate corresponding parts in theseveral views.

FIG. 1 shows a front elevation view in diagrammatic form of a vehicleincorporating the steering transmission of the present invention;

FIG. 2 is a plan view in a diagrammatic form of the vehicle of FIG. 1;

FIG. 3 is a front elevation view in diagrammatic form of a roller typevehicle shown in combination with the steering transmission of thepresent invention;

FIG. 4 is a plan view in a diagrammatic form of the vehicle shown inFIG. 3;

FIG. 5 shows a side elevation view in diagrammatic form of the vehicleand steering transmission apparatus of FIGS. 1 and 2, illustrating thearrangement of the gear shafts relative to each other;

FIG. 6 shows a side elevation view in diagrammatic form of the steeringtransmission apparatus and vehicle of FIG. 3, illustrating thearrangement of the gear shafts relative to each other;

FIG. 7 shows a diagrammatic end view of the steerable transmissionapparatus showing the relative position of the shafts with respect toeach other similar to the view of FIGS. 5 and 6;

FIG. 8 shows a section view through the transmission apparatus takenalong the line VIIIVIII of FIG. 7;

FIG. 9 shows a section view taken along the line IX-IX of FIG. 7;

FIG. 10 shows a section view taken along the line XX of FIG. 7; and

FIG. 11 shows a section view taken along the line XI-XI of FIG. 7.

DESCRIPTION OF SPECIFIC EMBODIMENTS As illustrated in FIGS. 1 and 2, avehicle 1 is shown having four wheels 2, 3, 4 and 5 used as drive wheelsfor traveling or propelling the vehicle over a surface. The wheels aredisposed in pairs on each side of the vehicle with the individual wheelsin the pairs located in tandem or longitudinal alignment. The wheelpairs 2, 3 and 4, 5 are mounted rigidly on the frame 6. The frame 6includes the side rails 7, 8 and the transverse spars or cross members9, 10. If desired, the vehicle 1 may be of the crawler track typewherein tracks 1 1, 11 are disposed in endless arrangement around therespective drive wheels on each side of the vehicle (FIG. 2). Thus, withthis latter arrangement the wheel pairs 2, 3 and 4, 5 do not comedirectly in contact with the surface but ride within and drive theendless tracks 11, 11. Each wheel in the pair is driven jointly with theother so that the wheel pair acts as a unit and moves together.

Intermediate gear trains 58, 59, 60, 61, 62 and 58', 59', 60', 61', 62'are mounted on their respective sides 7, 8 of the vehicle 1 eachinterconnecting and driving a pair of wheels.

Mounting on the vehicle 1 is a drive engine 12 which is interconnectedby a coupling to the steering transmission 13. In this embodiment boththe engine and the transmission apparatus are mounted in a generallycentral position on the vehicle. The output shafts 44, 44 of thetransmission are thus generally aligned with the drive pinion gears 58,58' for the wheel pairs 2, 3 and 4, 5.

By means of the steering transmission, independent and controlled driveto the wheel pair on each side of the vehicle can be obtained. Thus, thevehicle can be driven in either the forward or reverse direction atvarious speeds.

In FIGS. 3 and 4 another vehicle embodiment of this invention is shown.The roller type vehicle includes four rollers 2a, 3a, 4a, 5a which aregenerally driven in pairs arranged longitudinally on pach side of thevehicle. Each pair of rollers includes a narrow and a wide roller whichare arranged in staggered relation with the corresponding width of theopposite roller pair. As shown in FIG. 4 the widths of the rollersoverlap so that a seam in the rolled surface due to the inner edges ofroller pairs is eliminated. Each roller pair 2a, 3a and 4a, 5a aredriven independently in similar fashion as 'shown in FIGS. 1 and 2. Agear driven train 580, 59a, 60a, 61a, 62a drives the roller pair 4a, 5a.A similar gear driven train 58a, 59a, 60a, 61a, 62a, drives the oppositeroller pair 2a, 3a. Positioned on the vehicle is a driven engine 12ainterconnected by a coupling 2, with the steering transmission I3.Independent drive shafts 44a and 44a extend transversely from thetransmission 13 to drive the pinions 58a, 58a respectively.

The rollers which are normally used to compact the support surface canbe of the vibratory type. When this arrangement is desired, a powertake-off 73 is provided on the opposite end of the engine for drivingthe vibration apparatus of the individual rollers 20, 3a, 4a, 50.

As shown diagrammatically in FIG. 6, the engine 12a and the transmission13 are positioned transversely to the longitudinal axis of the vehicle.The transmission can thus be positioned in the space between the rollersallowing a direct gear drive arrangement and utilizing the availablespace between the rollers, thus providing a compact vehicle. Thisarrangement also provides that the vibration devices for each of therollers may be driven directly from the single drive enging 12a.

As shown in FIGS. 7-11 the transmission 13 includes a housing 14 withend walls 15, 16 and removable upper cover plate 17. The input drivenshaft 18 is connected to the engine 12 or 12a by means of a resilientclutch or coupling 19. The shaft 18 is rotatably mounted in the endwalls 15, 16 of the housing 14 by bearings 20, 21. Spur gears 22, 23having different diameters are drivingly connected to the shaft 18. Spurgear 22 meshes with gear 24 while gear 23 meshes with gear 25. The spurgears 24, 25 are mounted for rotational movement with respect tocoupling shaft 28 by means of anti-friction bearings 26, 27. Thecoupling shaft 28 is rotatably mounted in the housing by bearings 29,30. The drive gears 24, 25 are individually coupled to and uncoupledfrom the shaft 28 by means of respective clutches or coupling 31, 32.Both of the driven portions of the clutches 31, 32 are drivinglyconnected to the shaft 28 by means of a feather key 33. On one end ofthe coupling shaft 28 is mounted the driven gear 34 which in turn mesheswith the gear 35.

The gear 35 is mounted for rotational movement on forward gear shaft 36.It is to be understood that all of the power transmission shaftsdisclosed herein are mounted in the housing by means of suitable bearingmeans. A spur gear 37 which is mounted on the forward gear shaft 36meshes with gear 38 mounted by means of anti-friction bearings 40 oncoupling shaft 39. A coupling or clutch 41 is provided for drivinglyconnecting the gear 38 with the shaft 39. Also mounted on the couplingshaft 39 is the drive gear 50 which meshes with gear 43 mounted on driveshaft 44. (FIGS. 8 and Also mounted on the forward gear shaft 36 is gear35 which meshes with gear 46 mounted on shaft 45. A gear 47 which is ofsmaller diameter than the gear 46 is also mounted on the shaft 45 andmeshes directly with the teeth of gear 48. The gear wheel 48 is mountedfor rotational movement with respect to the coupling shaft 39 by meansof anti-friction bearing 49. The gear 48 can be secured to the shaft 39by means of the clutch or coupling 42 as desired. The correspondingdriven portion of each of the clutches 41, 42 are secured' to the shaft39 by means of featherkey 51. The coupling shaft 39 can be selectivelyrotated by engaging or coupling the clutches 41 or 42. Depending uponwhich clutch 41 or 42 is engaged with the coupling shaft 39, the reversegear shaft 45 can be interconnected so that the drive shaft 44 is drivenin the opposite direction for reverse travel, if desired.

The above described gear train arrangement thus affords a coupling.branch for driving the driven shaft 44 for either forward travel orreverse travel at one of two speeds.

In a similar manner a second gear train branch is obtained bysimultaneously meshing gear 24' with the gear 22 and 25' with gear 23.Thus, gear wheels 22, 23, which are drivenly mounted on input driveshaft 18, simultaneously and respectively mesh and drive the gears 24,24' and 25, 25'. The driven gears 24 and 25' are mounted for rotationalmovement with respect to the coupling shaft 28' by means ofanti-friction bearings 52a and 52b respectively. Separate clutches 31'and 32' respectively connect the driven gears 24 or 25' to the couplingshaft 28'. The driven portion of the clutches 31', 32' are connected tothe shaft 28' by means of feather key 53. Disposed on the coupling shaft28' is spur gear 34' which is directly meshedtwith gear wheel 35'. Thegear 35' is mounted on a second forward gear shaft 36' (FIG. 5). Mountedon the second forward gear shaft 36 is a gear 37 which meshes with gear38'. The gear 38 is mounted for rotational movement relative to couplingshaft 39' by means of anti-friction bearing 54. The rotationalconnection of the gear 38' with respect to the coupling shaft 39' may beobtained by means of clutch 41'. Also mounted on the coupling shaft 39'by means of rotational bearings 56 andclutch 42 is gear 48'. The drivenportion of the couplings 41 42' are drivingly connected to the shaft 39by means of feather key 55.

Also mounted on the coupling shaft 39' is gear wheel 50' positioned toengage gear 43'. The gear 43 is mounted in a driving connection to driveshaft 44'.

Also arranged in this second gear train is a second back or reverse gearshaft 45' for reversing the direction of rotation of the drive shaft 44'(FIG. 7). For this purpose, gear 35' meshes with gear 46 mounted on thereverse gear shaft 45 The smaller diameter gear 47'rotatessimultaneously with the shaft 45' and is meshed with the gear 48The gear 48' as explained above is operatively connected to the couplingshaft 39 through clutch 42". It is seen that the parallel gear traindriving the drive shaft 44 can by appropriate clutch actuation beselectively driven forward or backward in either of two speeds.

The shafts 43 and 44 as shown in this embodiment are alignedlongitudinally so that the drive connections on each side of thetransmission housing can be independently controlled and operated tosystematically drive separate members such as the drive wheel pairs orroller pairs described above. At theiends of the drive shaft 44, 44' aremounted pinion gears 57, 57' respectively. These pinion gears asillustrated in FIGS. 5 and 6 are drivingly connected to the drive gears58, 58' or 58a, 58a.

The engageable couplings or clutches are described in this embodiment asbeing of the hydraulic type. By the introduction of hydraulic pressureto the actuation plate of each clutch, a direct driven connection isobtained between the respective gear and shaft.

Hydraulic pump 63 is shown mounted on the side 16 i of the housing 14and directly connected to the input drive shaft 18 by means of acoupling or socket 64. Thus, hydraulic pressure for actuating of theclutches and control of the vehicle is obtained automatically when poweris obtained from the engine 12 or 12a. The hydraulic pump 63 as shownherein is of the gear wheel type but can be of any type desired.

Hydraulic pressure for actuation of the individual couplings istransmitted from the pump 63 by means of conduits 65, 66, 67, 68, 69,70, 71, 72. The conduits are connected directly to the ends of therespective coupling shafts. Each shaft has central bores or holesdrilled from each end partially the length of the, shaft whereby thepressure medium may be fed to the individual respective clutches (FIGS.8, 9 and 10). Hydraulic valves (not shown) are mounted in series withthe respective conduits to selectively control the clutch actuation.These valves may be mounted in any desired location such as on theexternal surface of the upper transmission plate 17. If desired, onedouble-acting hydraulic control valve may be connected to the conduitsof two clutches disposed on a single common shaft. The control lever canbe moved from a neutral position to either one or the other of theclutch actuation positions. Withthis arrangement, only half the numberof control levers relative to the number of clutches are re quired. Thecontrol levers may be arranged in accordance with their displacement toalign with the desired direction of travel.

OPERATION In the vehicles described herein which include the steeringtransmission apparatus described above, various movements can beeffected by proper clutch actuation. For forward travel of the vehiclein first gear or low speed (in the direction of the. arrows in FIGS. 1and 3), the clutches 31 and 31' and 41 and 41' are energized or engaged.For reverse travel in the first speed, the clutches 31 and 31 and 42and42' are to be engaged.

If it is desired that the vehicle is to travel forward at a secondspeed, the clutches 32 and 32' as well as 41 and 41 are to be engaged.In a like manner in the case of reverse travel in the second speed, theclutches 32 and 32' as well as 42 and 42' are engaged.

A vehicle of the present invention can rotate or turn on the spot" whenit may be necessary. For forward travel in a right turn it is necessaryto engage clutches 31, 31' and 41, 42. If it is desired to perform thismaneuver in the reverse direction, in other words in a right turnbackwards, it is only 'necessary to engage clutches 31, 31', 42 and 41'.For rotating on the spot in the forward direction and towards the left,clutches 31, 31', 42 and 41' are engaged. A reverse movement towards theleft requires the engagement of clutches 31, 31, 41 and 42'.

Wlth the steering transmission as described in this invention, it ispossible for the vehicle to travel along a curved path by driving one ofthe drive shafts 44, 44 at a higher speed than the other. For travelingon curves towards the right in a forward direction the clutches 32, 31',41 and 41' must be engaged. As can be seen, the right hand pair of drivewheels (looking towards the front of the vehicle) rotate at a lowerspeed than the left hand pair. For traveling in a curve towards theright in a reverse direction, the clutches 32, 31 and 42, 42' must bekept engaged.

In a like manner, if it is desired to travel in a forward directionwhile curving towards the left, it is necessary that the right hand pairof drive wheels travel at a higher speed than the left hand pair;therefore, for a forward curve towards the left clutches 32, 31, 41 and41 must be energized or engaged. For a similar curve but in the reversedirection, the clutches 32', 31, 42 and 42 must be engaged.

Irrespective of the speed or direction of travel of a vehicleincorporating the above steering transmission apparatus, it is foundthat the drive wheels or rollers are always directly connected by thegear drive. With this arrangement, the steering of the vehicle isaccurately controlled, particularly with respect to turns or curves ineither the forward or reverse direction. If desired, the transmissioncan be designed to include additional speed gears, thus providing athird, fourth, or more speed capability to the vehicle. By thisaddition, turns of various radii can be accomplished by varying theratio of speeds from one side to the other. It is further pointed outthat the drive wheels or rollers are always being driven so that noslipping or sliding with respect to the surface or pavement is possible.

The gearing arrangements which have been described for the presentsteering transmission allow the unit to be designed in a small andcompact fashion. Only spur gears are used throughout this device andthese gears are constantly meshed or engaged. There is no shifting ormeshing of gears as is found in the conventional transmission. The gearstogether with the clutches and shafts form a structurally rigid unit.The clutches require no separate space but are disposed directly on thecoupling shafts in the nonnally dead space usually present between thegears.

As mentioned above, the compact transmission apparatus as describedherein is ideally suited for use in a roller vehicle as shown in FIGS. 3and 4 due to the fact that the transmission can be shaped to fit intothe space between a pair of rolls. With this arrangement thetransmission can be positioned at a relatively low level with respect tothe roller axles, thus minimizing the interconnecting drive gearingnecessary for the transmission of power to the rolls.

The steering transmission described herein is suitable for all types ofvehicles having drive wheels, tracks, rollers or the like which arerigidly mounted on the frame. In addition, it is also possible to usethis transmission on boats, such as ferry boats, which have at least onepropulsion screw on each side of the centerline. With the instantsteering transmission it is thus possible to greatly improve themaneuverability of the boat by means of the independently controlledpropellers.

While the transmission apparatus and its combination with variousvehicles has been described in detail, it is obvious that this inventionis not to be considered as being limited to the exact form or usedisclosed and that changes in detail and construction may be madetherein within the scope of this invention without departing from thespirit thereof.

I claim:

1. In a roller-type vehicle including a frame, an engine supported onsaid frame, and a pair of compacting rollers supported on each of twoopposite sides of said frame and mounted for rotation about parallelaxes,

a. the improvement comprising compact transmission means fortransmitting power from said engine to each of said pairs of rollers,said transmission means comprising:

b. a housing,

0. an input shaft journaled in said housing operatively connected tosaid engine, and

d. first and second gear trains, each of said gear trains comprising e.a forward shaft journaled in said housing, a first pair of spur gears ofdifferent diameters fixed to said forward shaft, means for transmittingpower from said input shaft to said forward shaft,

a reverse shaft journaled in said housing in spaced relation to saidforward shaft, a second pair of spur gears of different diameter fixedto said reverse shaft,

g. one of said spur gears of said first pair on said forward shaft beingin constant mesh with one of said spur gears of said second pair on saidreverse shaft,

h. a coupling shaft journaled in said housing in spaced relation to bothsaid forward and reverse shafts, a third pair of spur gears of differentdiameters rotatably mounted on said coupling shaft, one of said spurgears of said third pair being in constant mesh with the other of saidspur gears of said first pair on said forward shaft and the other ofsaid spur gears of said third pair being in constant mesh with the otherof said spur gears of said second pair on said reverse shaft, anadditional spur gear fixed on said coupling shaft,

i. an output shaft journaled in said housing in spaced relation to saidcoupling shaft and drivingly coupled to one of said pairs of rollers, asingle spur gear fixed on said output shaft and in constant mesh withsaid additional spur gear on said coupling shaft, and

j. clutch means for individually coupling and uncoupling each of saidrotatably mounted spur gears of said third pair to and from saidcoupling shaft,

k. whereby each of said pairs of rollers may be driven independently ofthe other pair of rollers in both forward and reverse directions.

2. In a roller-type vehicle including a frame, an ento each of saidpairs of rollers, said transmission means comprising:

b. a housing,

c. an input shaft journaled in said housing operatively connected tosaid engine, a first pair of spur gears having different diameters fixedon said input shaft within said housing, and

d. first and second gear trains, each coupling said first pair of spurgears to one of said pair of rollers, each of said gear trainscomprising e. a coupling shaft journaled in said housing in spacedrelation to said input shaft, a second pair of spur gears havingdifferent diameters rotatably mounted on said coupling shaft, one ofsaid spur gears of said second pair being in constant mesh with one spurgear of said first pair and the other of said spur gears of said secondpair being in constant mesh with the other spur gear of said first pair,a further spur gear fixed on said coupling shaft,

f. a forward shaft journaled in said housing in spaced relation to saidcoupling shaft, a third pair of spur gears of different diameters fixedto said forward shaft,

g. a reverse shaft journaled in said housing in spaced relation to saidforward shaft, a fourth pair of spur gears of different diameters fixedto said reverse shaft,

h. one of said spur gears of said third pair on said forward shaft beingin constant mesh with both said further spur gear on said coupling shaftand one of 30 said spur gears of said fourth pair on said reverse shaft,

i. a further coupling shaft journaled in said housing in spaced relationto both said forward and reverse shafts, a fifth pair of spur gears ofdifferent diameters rotatably mounted on said further coupling shaft,one of said spur gears of said fifth pair being in constant mesh withthe other of said spur gears of said third pair on said forward shaftand the other of said spur gears of said fifth pair being in 40 constantmesh with the other of said spur gears of said fourth pair on saidreverse shaft, an additional spur gear fixed on said further couplingshaft,

j. an output shaft journaled in said housing in spaced relation to saidfurther coupling shaft and drivingly coupled to one of said pairs ofrollers, a single spur gear fixed on said output shaft and in constantmesh with said additional spur gear on said further coupling shaft, and

k. clutch means for individually coupling and uncoupling each of saidrotatably mounted spur gears of said second and fifth pairs to and fromtheir respective coupling shafts,

ll. whereby each of said pairs of rollers may be driven independently ofthe other pair of rollers at two different speeds in both the forwardand reverse directions.

3. A vehicle as defined in claim 2 wherein each of said rollers includesvibration means whereby each roller is vibrated, said vibration meansbeing driven by said engine.

4. A vehicle as defined in claim 2 wherein the rollers of each pair areof different lengths, the space between the rollers of one pair beingstaggered with respect to the space between the rollers of the otherpair.

5. A vehicle as defined in claim 2 wherein said clutch means comprisesan hydraulically operated clutch associated with each of said rotatablymounted spur gears of said second and fifth pairs for independentlycoupling and uncoupling said rotatably mounted spur gears to and fromtheir respective coupling shafts, said transmission means furthercomprising .a source of hydraulic power, conduit means between saidhydraulic power source and each of said clutches and valve means forcontrolling hydraulic power to each of said clutches.

6. A vehicle as defined in claim 5 wherein said valve means comprisestwo double acting valves, each for controlling a pair of clutches forcoupling and uncoupling one of said second and fifth pairs of spur gearsrotatably mounted on said respective coupling shafts.

1. In a roller-type vehicle including a frame, an engine supported onsaid frame, and a pair of compacting rollers supported on each of twoopposite sides of said frame and mounted for rotation about parallelaxes, a. the improvement comprising compact transmission means fortransmitting power from said engine to each of said pairs of rollers,said transmission means comprising: b. a housing, c. an input shaftjournaled in said housing operatively connected to said engine, and d.first and second gear trains, each of said gear trains comprising e. aforward shaft journaled in said housing, a first pair of spur gears ofdifferent diameters fixed to said forward shaft, means for transmittingpower from said input shaft to said forward shaft, f. a reverse shaftjournaled in said housing in spaced relation to said forward shaft, asecond pair of spur gears of different diameter fixed to said reverseshaft, g. one of said spur gears of said first pair on said forwardshaft being in constant mesh with one of said spur gears of said secondpair on said reverse shaft, h. a coupling shaft journaled in saidhousing in spaced relation to both said forward and reverse shafts, athird pair of spur gears of different diameters rotatably mounted onsaid coupling shaft, one of said spur gears of said third pair being inconstant mesh with the other of said spur gears of said first pair onsaid forward shaft and the other of said spur gears of said third pairbeing in constant mesh with the other of said spur gears of said secondpair on said reverse shaft, an additional spur gear fixed on saidcoupling shaft, i. an output shaft journaled in said housing in spacedrelation to said coupling shaft and drivIngly coupled to one of saidpairs of rollers, a single spur gear fixed on said output shaft and inconstant mesh with said additional spur gear on said coupling shaft, andj. clutch means for individually coupling and uncoupling each of saidrotatably mounted spur gears of said third pair to and from saidcoupling shaft, k. whereby each of said pairs of rollers may be drivenindependently of the other pair of rollers in both forward and reversedirections.
 2. In a roller-type vehicle including a frame, an enginesupported on said frame, and a pair of compacting rollers supported oneach of two opposite sides of said frame and mounted for rotation aboutparallel axes, a. the improvement comprising compact transmission meansfor transmitting power from said engine to each of said pairs ofrollers, said transmission means comprising: b. a housing, c. an inputshaft journaled in said housing operatively connected to said engine, afirst pair of spur gears having different diameters fixed on said inputshaft within said housing, and d. first and second gear trains, eachcoupling said first pair of spur gears to one of said pair of rollers,each of said gear trains comprising e. a coupling shaft journaled insaid housing in spaced relation to said input shaft, a second pair ofspur gears having different diameters rotatably mounted on said couplingshaft, one of said spur gears of said second pair being in constant meshwith one spur gear of said first pair and the other of said spur gearsof said second pair being in constant mesh with the other spur gear ofsaid first pair, a further spur gear fixed on said coupling shaft, f. aforward shaft journaled in said housing in spaced relation to saidcoupling shaft, a third pair of spur gears of different diameters fixedto said forward shaft, g. a reverse shaft journaled in said housing inspaced relation to said forward shaft, a fourth pair of spur gears ofdifferent diameters fixed to said reverse shaft, h. one of said spurgears of said third pair on said forward shaft being in constant meshwith both said further spur gear on said coupling shaft and one of saidspur gears of said fourth pair on said reverse shaft, i. a furthercoupling shaft journaled in said housing in spaced relation to both saidforward and reverse shafts, a fifth pair of spur gears of differentdiameters rotatably mounted on said further coupling shaft, one of saidspur gears of said fifth pair being in constant mesh with the other ofsaid spur gears of said third pair on said forward shaft and the otherof said spur gears of said fifth pair being in constant mesh with theother of said spur gears of said fourth pair on said reverse shaft, anadditional spur gear fixed on said further coupling shaft, j. an outputshaft journaled in said housing in spaced relation to said furthercoupling shaft and drivingly coupled to one of said pairs of rollers, asingle spur gear fixed on said output shaft and in constant mesh withsaid additional spur gear on said further coupling shaft, and k. clutchmeans for individually coupling and uncoupling each of said rotatablymounted spur gears of said second and fifth pairs to and from theirrespective coupling shafts,
 3. A vehicle as defined in claim 2 whereineach of said rollers includes vibration means whereby each roller isvibrated, said vibration means being driven by said engine.
 4. A vehicleas defined in claim 2 wherein the rollers of each pair are of differentlengths, the space between the rollers of one pair being staggered withrespect to the space between the rollers of the other pair.
 5. A vehicleas defined in claim 2 wherein said clutch means comprises anhydraulically operated clutch associated with each of said rotatablymounted spur gears of said second and fifth pairs for independentlycoupling and uncoupling said rotatably mounted spur gears to and fromtheir respective coupling shafts, said transmission means furthercomprising a source of hydraulic power, conduit means between saidhydraulic power source and each of said clutches and valve means forcontrolling hydraulic power to each of said clutches.
 6. A vehicle asdefined in claim 5 wherein said valve means comprises two double actingvalves, each for controlling a pair of clutches for coupling anduncoupling one of said second and fifth pairs of spur gears rotatablymounted on said respective coupling shafts.